Fabrication of stretchable ion gels based on semicrystalline random copolymers

초록

We fabricated a flexible and stretchable ionic gel based on a copolymer with low crystallinity. In the previous study, we fabricated ion gels using crystals of long side chain as a physical crosslinking point. However, there was a limit to application to flexible electrolytes due to their low stretchability and flexibility. In this study, we tried to fabricate an ionic gel having stretchability and flexibility by reducing the ratio of crystals. We randomly copolymerized tert-butyl acrylate as an amorphous monomer and behenyl acrylate as a crystalline side chain monomer by free radical polymerization in various ratios. Unlike before, it was attempted to obtain a copolymer with low crystallinity by reducing the ratio of behenyl acrylate. As a result, the synthesized copolymer had a lower degree of crystallinity than the previous study, and some crystals were hardly seen in some ratios. An ionic gel was prepared using these copolymers and an ionic liquid, and we measured the thermal, mechanical properties and ionic conductivity of the ionic gel. Through UTM, it was confirmed that the ionic gel having a low crystallinity has good stretchability compared to the previous one. In the previous study, young's modulus was high, but elongation was small, and toughness was small (59?110 kJ/m3). On the other hand, in this study, young's modulus was not as large as the previous one (3MPa), but elongation increased (~1000%) due to its good stretching ability. As a result, the toughness increased significantly (3.5-11.7 MJ/m3).